Organic Remediation Research Articles

Alternative and Herbal Pharmaceuticals

Alternative and herbal pharmaceuticals have gained significant attention in recent years as completing approaches to conventional medicine. This review explores the increasing interest in these organic remedies, meeting their productiveness, security, and supervisory challenges. Herbal medicines, arisen plants, and floral beginnings have existed secondhand for centuries in differing breedings for their healing features. The revival of interest in this natural device is compelled by one growing demand for whole and deterrent healthcare options. This review explains the pharmacological exercises of key herbaceous compounds, their machines of operation, and the clinical evidence advocating their use. Additionally, the unification of alternative healings into prevailing healthcare is checked, highlighting the significance of control of product quality, uniformity, and severe dispassionate experiments. While alternative and herbal pharmaceuticals offer hopeful benefits, they too pose challenges, containing instability in effectiveness and potential interactions accompanying unoriginal drugs. The review underlines the need for more inclusive research to confirm the efficacy and security of these analyses. In conclusion, alternative and herbaceous pharmaceuticals show a valuable addition to the healthcare arsenal, supported they are secondhand sensibly and as well evidence-located practices. Future research guidance and policy approvals are projected to embellish the unification of these healings into modern healing practice.

Geochip 5.0 insights into the association between bioleaching of heavy metals from contaminated sediment and functional genes expressed in consortiums.

The heavy metal contamination in river and lake sediments endangers aquatic ecosystems. Herein, the feasibility of applying different exogenous mesophile consortiums in bioleaching multiple heavy metal-contaminated sediments from Xiangjiang River was investigated, and a comprehensive functional gene array (GeoChip 5.0) was used to analyze the functional gene expression to reveal the intrinsic association between metal solubilization efficiency and consortium structure. Among four consortiums, the Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans consortium had the highest solubilization efficiencies of Cu, Pb, Zn, and Cd after 15days, reaching 50.33, 29.93, 47.49, and 79.65%, while Cu, Pb, and Hg had the highest solubilization efficiencies after 30days, reaching 63.67, 45.33, and 52.07%. Geochip analysis revealed that 31,346 genes involved in different biogeochemical processes had been detected, and the systems of 15days had lower proportions of unique genes than those of 30days. Samples from the same stage had more genes overlapping with each other than those from different stages. Plentiful metal-resistant and organic remediation genes were also detected, which means the metal detoxification and organic pollutant degradation had happened with the bioleaching process. The Mantel test revealed that Pb, Zn, As, Cd, and Hg solubilized from sediment influenced the structure of expressed microbial functional genes during bioleaching. This work employed GeoChip to demonstrate the intrinsic association between functional gene expression of mesophile consortiums and the bioleaching efficiency of heavy metal-contaminated sediment, and it provides a good reference for future microbial consortium design and remediation of river and lake sediments.

Virtual Screening and Network Pharmacology-Based Study to Explore the Pharmacological Mechanism of Vitis Venifera (Grapes) for Anti-Breast Cancer Treatment

Background: Breast cancer is a significant global concern, with its burden increasing worldwide. Projections for the coming decades indicate that a substantial proportion of the disease's incidence and mortality will affect underprivileged groups. There is enormous potential in natural products for developing therapeutic agents for breast cancer prevention and treatment. However, research evidence is essential to establish the effectiveness of these organic remedies. Objectives: Using a network ethnopharmacological framework, this study aims to assess the anti-breast cancer effects of Vitis vinifera (grapes), traditionally believed to have anticancer properties. Methods: The study utilized polypharmacological screening to gather information about Vitis vinifera (grapes) from multiple databases. It investigated the relationship between specific bioactives found in Vitis vinifera and targets associated with breast cancer using Binding DB. Results: The network analysis revealed ten potential bioactives interacting with 17 targets related to breast cancer. Among these, quercetin and kaempferol showed a higher number of interactions with the identified targets in the study. Conclusions: The research conducted an in-silico investigation of the cellular mechanisms by which specific bioactive phytoconstituents from Vitis Vinifera influence the inhibition of several targets involved in breast cancer.

Hydroponic Trough Systems for Maximising Cucumber Production

Abstract: Hydroponics is a promising solution to address the increasing demand for food caused by limited arable land and a growing global population. This article focuses on the use of hydroponics in cucumber cultivation, specifically highlighting the adaptability of hydroponic trough system. It explains the design elements of the trough system in detail, including configuration, growing medium, nutrient solution, and support structures. The article emphasises the advantages of hydroponic trough systems in cucumber cultivation, such as precise nutrient dispensation, space efficiency, water conservation, and potential for automation. It discusses strategies for optimal cucumber production within these systems, including temperature control, pollination techniques, pruning, and pH monitoring. The article also addresses the challenges of insect and pest attacks, introducing common pests and presenting integrated pest management strategies for effective control. It explores diseases that can affect cucumber crops in hydroponic systems, such as powdery mildew, downy mildew, Pythium root rot, and Fusarium wilt. It discusses strategies to prevent these diseases, including preventive measures, disease-resistant cucumber varieties, cultural practices, and bio methods. By considering all these aspects, a comprehensive approach to disease management can be established. Overall, adopting hydroponic trough systems in cucumber cultivation offers a sustainable and efficient solution to traditional farming challenges. By incorporating preventive measures, disease-resistant cultivars, and organic remedies, farmers can ensure a thriving cucumber harvest and contribute to a productive and sustainable agricultural future.

Optimizing ciprofloxacin removal from water using jamun seed (Syzygium cumini) biochar: A sustainable approach for ecological protection

Scientific interest in antimicrobial pollutants, such as ciprofloxacin, has increased. Due to spread of antibiotic-resistant bacteria, resistance genes, and their dissemination to the environment. Therefore, their remediation is necessary to ensure ecological sustainability. The current study aimed to optimise the removal of ciprofloxacin from synthetic water using jamun seed (JS) (Syzygium cumini) biochar using a response surface methodology (RSM). Result indicates ciprofloxacin elimination efficiency ranged between 32.46 and 94.95%, indicating the material can be improved and used for remediation of organics. The residual standard error of 4.4% were found for the predicted model, implying that the model is credible and can be used to predict future experimental findings. The R-squarred value for the improved Langmuir model's R2 is 0.9681 which is inclose agreement with the Freundlich isotherm, R2 0.9757. Therefore, JS biochar could be utilized for the remediation of ciprofloxacin from contaminated water and wastewater for ecological safety and sustainability.

Microcystis blooms caused the decreasing richness of and interactions between free-living microbial functional genes in Lake Taihu, China.

Microcystis blooms have a marked effect on microbial taxonomical diversity in eutrophic lakes, but their influence on the composition of microbial functional genes is still unclear. In this study, the free-living microbial functional genes (FMFG) composition was investigated in the period before Microcystis blooms (March) and during Microcystis blooms (July) using a comprehensive functional gene array (GeoChip 5.0). The composition and richness of FMFG in the water column was significantly different between these two periods. The FMFG in March was enriched in the functional categories of nitrogen, sulfur, and phosphorus cycling, whereas the FMFG in July was enriched in carbon cycling, organic remediation, and metal homeostasis. Molecular ecological network analysis further demonstrated fewer functional gene interactions and reduced complexity in July than in March. Module hubs of the March network were mediated by functional genes associated with carbon, nitrogen, sulfur, and phosphorus, whereas those in July by a metal homeostasis functional gene. We also observed stronger deterministic processes in the FMFG assembly in July than in March. Collectively, this study demonstrated that Microcystis blooms induced significant changes in FMFG composition and metabolic potential, and abundance-information, which can support the understanding and management of biogeochemical cycling in eutrophic lake ecosystems.

Functional gene composition and metabolic potential of deep-sea coral-associated microbial communities

Over the past decade, an abundance of 16S rRNA gene surveys have provided microbiologists with data regarding the prokaryotes present in a coral-associated microbial community. Functional gene studies that provide information regarding what those microbes might do are fewer, particularly for non-tropical corals. Using the GeoChip 5.0S microarray, we present a functional gene study of microbiomes from five species of cold-water corals collected from depths of 296–1567 m. These species included two octocorals, Acanthogorgia aspera and Acanthogorgia spissa, and three stony corals: Desmophyllum dianthus, Desmophyllum pertusum (formerly Lophelia pertusa), and Enallopsammia profunda. A total of 24,281 gene sequences (representing different microbial taxa) encoding for 383 functional gene families and representing 9 metabolic gene categories were identified. Gene categories included metabolism of carbon, nitrogen, phosphorus, and sulfur, as well as virulence, organic remediation, metal homeostasis, secondary metabolism and phylogeny. We found that microbiomes from Acanthogorgia spp. were the most functionally distinct but also least diverse compared against those from stony corals. Desmophyllum spp. microbiomes were more similar to each other than to E. profunda. Of 383 total gene families detected in this study, less than 20% were significantly different among these deep-water coral species. Similarly, out of 59 metabolic sub-categories for which we were able to make a direct comparison to microbiomes of tropical corals, only 7 were notably different: anaerobic ammonium oxidation (anammox), chitin degradation, and dimethylsulfoniopropionate (DMSP) degradation, all of which had higher representations in deep-water corals; and chromium homeostasis/resistance, copper homeostasis/resistance, antibiotic resistance, and methanogenesis, all of which had higher representation in tropical corals. This implies a broad-scale convergence of the microbial functional genes present within the coral holobiont, independent of coral species, depth, symbiont status, and morphology.

Targeting Nrf2 signaling pathway by quercetin in the prevention and treatment of neurological disorders: An overview and update on new developments.

Neurological disorders (NLDs) are widely acknowledged as a significant public health concern worldwide. Stroke, Alzheimer's disease (AD), and traumatic brain injury (TBI) are three of these disorders that have sparked major study attention. Neurological dysfunction, protein buildup, oxidation and neuronal injury, and aberrant mitochondria are all prevalent neuropathological hallmarks of these disorders. The signaling cascade of nuclear factor erythroid 2 related factor 2 (Nrf2) shares all of them as a common target. Several studies have found that overexpression of Nrf2 is a promising treatment method in NLDs. Effective treatment of these disorders continues to be a universal concern regardless of various medicines. In order to treat a variety of neurological problems, organic remedies may provide an alternative treatment. It has been demonstrated that polyphenols like quercetin (Que) offer considerable capabilities for treating NLDs. One of Que's greatest key targets, Nrf2, has the capacity to control the production of a number of cytoprotective enzymes that exhibit neuroprotective, detoxifying, and antioxidative effects. Additionally, Que enhanced the expression of Nrf2 and inhibited alterations in the shape and death of neurons in the hippocampus. In this review, we have focused on Que's medicinal prospects as a neuroprotective drug. PubMed, Scopus, Science Direct, and Google Scholar were used to search articles for this study. The findings of this research demonstrate that (1) Que protected the blood-brain barrier via stimulating Nrf2 in animal stroke, which alleviated ischemic reperfusion and motor dysfunction. (2) By triggering the Nrf2 pathway, Que reduced the neuroinflammation and oxidative damage brought on by TBI in the cortex. (3) In an experimental model of AD, Que enhanced cognitive function by decreasing A1-4, antioxidant activity, and Nrf2 levels in the brain. We discuss recent research on Que-mediated Nrf2 expression in the management of several NLDs in this paper.

Smart Agriculture

Agriculture is the primary main stay of the economy in our country. In recent years, because of uncertain trends in climate and policy making this has attributed to the price of crops becoming highly volatile. Farmers remain oblivious of these uncertainties, which attribute a degradation of the farmers’ mental and financial wellbeing. The excessive use of chemicals in the soil have caused the soil to lose its organic properties ultimately causing the soil to be exothermic in nature, hence requiring large amounts of water for maintenance of the farm land with an unhealthy quality of production causing wide spread devastation to the overall economy and health of a country. This inspired us to create a system which is handy, easy-to-use and breaks the farmers from the shackles of the large chemical fertilizer corporations, to detect the plant disease early and the harvest optimal crop for better productivity. This system provides accurate results in predicting the optimum crop according to the location and soil conditions. The system frame work in corporate disease detection and fertilizer recommendation all with a custom dataset of organic remedies for the relevant diseases detected

Synthesis of SnO2 nanoparticles coated ZnO–g–C3N4 composite nanostructures with novel antibacterial activity

Abstract In this work, composite nanostructures (CNs) of SnO2–ZnO–g–C3N4 have been prepared by a soft chemical method and investigated for their potential application in photocatalytic remediation of organics in water and antibacterial agents. Structural study revealed the presence of three phases related to hexagonal wurtzite phase of ZnO, tetragonal phase of SnO2 and monoclinic phase of g–C3N4 having nanocrystalline nature which confirms the formation of CNs. Formation of nanoscale morphology along with elemental composition of the CNs have been validated through scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) spectroscopy. The presence of only A 1g mode of SnO2 in Raman spectrum of ternary CNs suggested that SnO2 nanoparticles have been coated on the surfaces of ZnO and g–C3N4 which is also evident from SEM results. SnO2–ZnO–g–C3N4 CNs have shown much higher photocatalytic degradation efficiency and produced 7 mm greater zone of inhibition (ZOI) against Gram-positive S. Aureus bacteria as compared to pure ZnO which is quite significant result when compared to previously reported results for SnO2–ZnO CNs. These synthesized CNs may have potential uses in healthcare technology and treatment of organics in water.

Unexpected enrichment of antibiotic resistance genes and organic remediation genes in high-altitude lakes at Eastern Tibetan Plateau

Elevation has a strong effect on aquatic microbiome. However, we know little about the effects of elevation on functional genes, especially antibiotic resistance genes (ARGs) and organic remediation genes (ORGs) in freshwater ecosystems. In this study, we analyzed five classes of functional genes including ARGs, metal resistance genes (MRGs), ORGs, bacteriophages, and virulence genes between two high-altitude lakes (HALs) and two low-altitude lakes (LALs) in Mountain Siguniang at Eastern Tibetan Plateau by means of GeoChip 5.0. No differences (Student's t-test, p > 0.05) of gene richness including ARGs, MRGs, ORGs, bacteriophages, and virulence genes in HALs and LALs were found. The abundance of most ARGs and ORGs was higher in HALs than in LALs. For MRGs, the abundance of macro metal resistance genes of potassium, calcium, and aluminum was higher in HALs than in LALs (Student's t-test, p < 0.05; all Cohen's d > 0.8). The abundance of some heavy metal resistance genes of lead and mercury was lower in HALs than in LALs (Student's t-test, p < 0.05; all Cohen's d < −0.8). The composition of these functional genes in HALs differed significantly from in LALs. The functional gene network in HALs was also more complex than that in LALs. We speculate that enrichment of ARGs and ORGs in HALs is related to different microbial communities, exogenous ARGs, and enriched persistent organic pollutants through long-range atmospheric transport driven by the Indian monsoon. This study highlights the unexpected enrichment of ARGs, MRGs, and ORGs in remote lakes at high elevations.

Exceptional visible-light photoelectrocatalytic activity of dual Z-scheme Bi@BiOI-Bi2O3/C3N4 heterojunction for simultaneous remediation of Cr(VI) and phenol

Developing highly efficient and stable photocatalysts remains a major challenge for the remediation of environmental pollutants. In this work, the Bi0 decorated BiOI-Bi2O3/C3N4 heterojunction (Bi@BiOI-Bi2O3/C3N4) film was fabricated through ultrasonic stripping, I− etching and in situ UV-reduction processes and then characterized thoroughly by various analytical techniques. The characteristics of simultaneous mitigation of phenol and Cr(VI) were evaluated over Bi@BiOI-Bi2O3/C3N4 photoanode under visible light. The results exhibited that both phenol and Cr(VI) were removed completely by the photoanode at 2.5 V within 1.5 h, superior to our previous report. The synergy of the surface plasmon resonance (SPR) effect of Bi0 and ternary heterojunction accelerated the separation and transfer of photo-induced charge carrier and thus heavily promoted the removal efficiency. Moreover, the excellent stability of this photoanode was hold with no considerably activity attenuation after 4 cycles. Finally, a dual Z-scheme charge transfer process was presented. This work offers an attractive pathway to construct highly active photoelectrode with promising application for simultaneous remediation of organics and heavy metals in wastewater.

Cyclodextrin-functionalized magnetic alginate microspheres for synchronous removal of lead and bisphenol a from contaminated soil

Currently, functional materials-based soil remediation focused on the stabilization of heavy metals and organics to inhibit their migration, however, the possible second release of these pollutants caused by soil condition variation attracts broad attention. Herein, β-cyclodextrin functionalized magnetic sodium alginate microspheres (MSA-CDMW) were fast and facilely synthesized through microwave-assisted one-pot method for synchronous detachment of Pb and BPA from contaminated soil. The obtained MSA-CDMW presented wide pH adaptability and fast capture for Pb(II)/BPA with superior adsorption capacity of 369.03/165.37 mg/g. Furthermore, the effects of material dosage and soil pH on the remediation ability of MSA-CDMW were explored in detail. After adding 5% MSA-CDMW into the contaminated soil for 3-round successive remediation (12 h for each round), the amount of extractable Pb and total BPA was simultaneously decreased by 56.30 and 0.78 mg/kg, respectively. Meanwhile, the quantity of exchangeable and carbonate bound Pb was significantly decreased to 7.13% with transformation into relatively stable fractions. A series of characterizations revealed that ion exchange, pore filling, complexation, and electrostatic attraction were responsible for Pb binding, while MSA-CDMW could capture BPA through host-guest interaction by the hydrophobic cavity of β-cyclodextrin. Additionally, recovery and floatation results revealed that the MSA-CDMW could be easily separated from the soil using magnets even at extreme drying and wetting conditions, thus providing a novel, fast, and eco-friendly strategy for effective remediation of heavy metals and organics contaminated soil.

Soil Chemical Pollution and Military Actions: A Bibliometric Analysis

Contrary to the optimistic expectations three decades ago, global military expenditure is increasing rather rapidly, fueled by the increasing intensity of international tensions. As a consequence of this, the military-caused soil pollution gains in importance. On the basis of a bibliometric analysis of 3500 articles, it is obvious that the level of interest in this topic has been rather fluctuating in the last decades, but in the last years, more than two hundred and fifty new publications have been appearing annually. The majority of publications are authored by US, Chinese, and Western European authors. Five main research areas could be identified by the cluster analysis of the following keywords: Heavy metal pollution, water resource pollution, consequences of soil pollution in the food chain, pollution by organic components and soil remediation, and analytic method development. The most central problem of research is heavy metal contamination. The basic topics of research are risk management, water contamination, and the depleted uranium problem. There is a further need to study the possibilities of decreasing of level of chemical pollutants, especially heavy metals.

Tuning of Carbon Microspheres and Graphene Structures with Hetero Atoms for Organic Dye Degradation and Heavy Metal Remediation - Influence of Fructose as a Precursor

In today’s context, there is a tremendous potential for the design of smart nanomaterials of carbon origin for multi-dimensional applications. The role-play of precursor is significant in the design of nanometric carbon materials apart from other experimental parameters. Correlation of the synthetic methodology, the microstructure of the product helps to tune and widen the applications aspect. The present study aimed to tune the simple ketose (reducing monosaccharide) of fructose to functionalize (with O, N, and S atoms) carbon layers, microspheres of carbon, to optimize the experimental conditions, and to establish the mechanism involved in the process. The study further explored the catalytic ability of the carbon samples in the degradation of thiazine and xanthene-based textile dyes and the sensing of heavy metal ions of chromium and copper. A simple hydrothermal process, fructose as a precursor, alkaline pH, and appropriate calcination temperature provided micro and nanostructures of carbon viz. carbon microspheres (CMs), graphene oxide (GO), sulfur doped graphene oxide (S-GO), and nitrogen-doped reduced graphene oxide (N-rGO). In this study a simple mechanism for the conversion process is suggested. Further, the results of the preliminary screening study on the catalytic ability of the sulfur and nitrogen-doped graphene samples in the presence of UV and Visible light upon the degradation of methylene blue (MB), methyl orange (MO), Rhodamine-B (Rh-B) dyes were satisfactory. The adsorbent and the ion exchange capacity of the carbon microspheres were found to be excellent. The results of the study will contribute positively to the treatment and management of industrial wastewater.

Alterations of endophytic microbial community function in Spartina alterniflora as a result of crude oil exposure.

The 2010 Deepwater Horizon disaster remains one of the largest oil spills in history. This event caused significant damage to coastal ecosystems, the full extent of which has yet to be fully determined. Crude oil contains toxic heavy metals and substances such as polycyclic aromatic hydrocarbons that are detrimental to some microbial species and may be used as food and energy resources by others. As a result, oil spills have the potential to cause significant shifts in microbial communities. This study assessed the impact of oil contamination on the function of endophytic microbial communities associated with saltmarsh cordgrass (Spartina alterniflora). Soil samples were collected from two locations in coastal Louisiana, USA: one severely affected by the Deepwater Horizon oil spill and one relatively unaffected location. Spartina alterniflora seedlings were grown in both soil samples in greenhouses, and GeoChip 5.0 was used to evaluate the endophytic microbial metatranscriptome shifts in response to host plant oil exposure. Oil exposure was associated with significant shifts in microbial gene expression in functional categories related to carbon cycling, virulence, metal homeostasis, organic remediation, and phosphorus utilization. Notably, significant increases in expression were observed in genes related to metal detoxification with the exception of chromium, and both significant increases and decreases in expression were observed in functional gene subcategories related to hydrocarbon metabolism. These findings show that host oil exposure elicits multiple changes in gene expression from their endophytic microbial communities, producing effects that may potentially impact host plant fitness.

Microbial community structure and metabolic potential in the coastal sediments around the Yellow River Estuary

The Yellow River Estuary and Laizhou Bay are located on the northern Shandong Peninsula in the Bohai Sea in China and have been polluted by intensive anthropogenic activity. However, few studies have focused on the effect of these activities on the microbial communities and their ecological functions in this area. In this study, the combination of 16S rDNA gene sequencing and GeoChip technology was used to analyzed the microbial community component and their functional genes. Thaumarchaeot and Bacteroidetes are the most abundant phyla. The results of correlation analysis and redundancy analysis (RDA) showed water depth (r2 = 0.76, P = 0.005), total Na content (r2 = 0.63, P = 0.021) and total Ca content (r2 = 0.53, P = 0.05) in the sediments were the most significant environmental factors affecting the microbial community. The diversity of the microbial community and signal intensity of functional genes at nearshore sites (N sites) were higher than that at the offshore sites (O sites), but the component of microbial community and functional genes was similar in general. Functional genes for C, N, P and S cycle were detected at both nearshore and offshore sites, which illustrated that microbial communities were active in nutrient cycle. Proteobacteria contributes significantly to material cycle in microbial community. In addition, functional genes related to organic remediation and metal detoxification are also abundant. It indicated that the environmental pollution caused by anthropogenic activities has greatly affected the microbial community components and their biochemical functions in the Yellow River Estuary and surrounding areas. This study reveals the effect of anthropogenic activities on microbial communities and provides the basis for environmental management.

Hazardous Waste Management Approach for Heavy Metals in Soil by Phytoremediation

There have been a lot of practical applications of phytoremediation in the last ten years, involving organic, inorganic, heavy metal, and radionuclide remediation. India would find this to be an excellent alternative to conventional remediation methods as it is a sustainable and inexpensive process. The huge retention of industrial waste in soil resulted in soil pollution which is more hazardous due to the long-term persistence of contaminants. A major source of hazardous waste products in Bhopal city is the industrial region. Near residential areas, industries produce pollution that can be very harmful to human health. The objective of this research was to determine which heavy metal accumulators are capable of absorption and translocation of heavy metals. In the Govindpura sampling sites, Cr and Ni concentrations were higher, while Cd concentrations were lower. Phytoremediation was conducted by comparing the heavy metal accumulation of Datura inoxia, Calotropis procera, Ricinus commmunis, and Polygonum in vitro cultures.

A functional gene-array analysis of microbial communities settling on microplastics in a peat-draining environment

Concerns about microplastic (MP) pollution arise from the rafting potential of these durable particles which potentially propagate harmful chemicals and bacteria across wide spatial gradients. While many studies have been conducted in the marine environment, knowledge of MPs in coastal and freshwater systems is limited. For this study, we exposed two MPs (polyethylene terephthalate and polylactic acid) to the undisturbed peat-draining Maludam River in Malaysia, for 6 months. The microbial communities on these MPs and the surrounding water were sequenced by MiSeq, while the genetic responses of these communities were assessed by GeoChip 5.0S. Microbial communities were dominated by the phyla Proteobacteria, Acidobacteria and Actinobacteria. Metabolic processes involved with carbon, nitrogen, sulfur, metal homeostasis, organic remediation and virulence had significantly different gene expression among the communities on MPs and in the surrounding water. Our study is the first to look at changes in gene expression of whole plastisphere communities.

The dominant effect of black carbon on the chemical degradability of PCB1: Sequestration or/and catalysis

Black carbon (BC) plays a crucial role in the migration, transformation, and remediation of hydrophobic organics (HOCs) in soil/sediment. Previous studies mainly focus on the sorption characteristic of BC, while the chemical degradability of HOCs, which is affected by sequestration and catalytic effects of BC, has not yet been systematically studied. In this study, the dechlorination process of 2-chlorobiphenyl (PCB1), adsorbed on BC prepared at different pyrolysis temperatures, by bimetal modified nano zero-valent iron (nZVI/Pd) was investigated. The results showed that, on the one hand, adsorption limited the dechlorination process. PCB1 in the resistant desorption state exhibited lower degradation efficiency than that in other adsorption state. On the other hand, the catalysis of high-temperature BC reduced the inhibition of adsorption on dechlorination to some extent. As the pyrolysis temperature rose from 400 °C to 900 °C, the degradation efficiency of adsorbed PCB1 within 48 h improved from 53.5% to 95.3%, and the rate constant (kobs) increased from 0.104 h−1 to 0.197 h−1. High-temperature BC promoted the electrons release of Fe0 and the generation of [H], and its conductivity improved the electron utilization efficiency so that the dechlorination reaction could proceed both on the surface of nZVI/Pd particles and BC, thereby promoting the dechlorination of PCB1. Therefore, adsorption effect dominated degradability of PCB1 sequestrated by low-temperature BC, while for high-temperature BC, synergistic catalytic effect played a dominant role. These findings indicate that reductive efficiency of nZVI should be systematically evaluated according to different types of BC in soil/sediment.